Effects of the Jendrassik manoeuvre on muscle spindle activity in man.
Open accessAbstract
Twenty-eight mechanoreceptive units identified as primary or secondary spindle afferents were sampled from muscle nerve fascicles in the median, peroneal, and tibial nerves of healthy adult subjects. The responses of these units to sustained passive muscle stretch, to passive stretching movements, to tendon taps, and electrically-induced muscle twitches were studied while the subject performed repeated Jendrassik manoeuvres involving strong voluntary contractions in distant muscle groups. The manoeuvres had no effect upon the afferent spindle discharges as long as there were no EMG signs of unintentional contractions occurring in the receptor-bearing muscle and no mechanotransducer signs of unintentional positional changes altering the load on that muscle. Unintentional contractions in the receptor-bearing muscle frequently occurred during the manoeuvres, however, and then coactivation of the spindle afferents was observed. Multiunit afferent responses to Achilles tendon taps, led off from tibial nerve fascicles, were in a similar way uninfluenced by the Jendrassik manoeuvres, even when these resulted in marked reinforcement of the calf muscle tendon jerk. The results provide no evidence for fusimotor sensitization of spindles in muscles remaining relaxed during the Jendrassik manoeuvre, and reflex reinforcement occurring without concomitant signs of active tension rise in the muscles tested is presumed to depend upon altered processing of the afferent volleys within the cord.
AI snapshot
Written from the paper’s full text.
TL;DR
This study tested whether the Jendrassik manoeuvre increases muscle spindle afferent activity in relaxed human muscles. It found no evidence for fusimotor sensitization when receptor-bearing muscles stayed relaxed; apparent spindle changes accompanied unintentional extrafusal contractions or load changes, and tendon-jerk reinforcement was attributed to altered central processing.
Key findings
- In 28 identified spindle afferents from median, peroneal, and tibial muscle nerve fascicles, Jendrassik manoeuvres had no effect on discharge when EMG and torque showed no unintentional contraction or positional change in the receptor-bearing muscle.
- Among 30 mechanoreceptive units, 15 were unaffected; in the other 15, changes were mostly non-reproducible, and all changes coincided with EMG or torque evidence of extrafusal activity or altered load. Only four spindle afferents increased firing in every manoeuvre tested.
- Multiunit tibial nerve responses to Achilles tendon taps did not increase during reinforcement, even when reflex torque and EMG were larger; the afferent volley produced by percussion was unchanged.
- Non-spindle activity could be modified: a Golgi tendon organ Ib fibre increased firing with unintentional forearm tension, and sympathetic efferent bursts increased during forceful manoeuvres, but spindle activity did not.
Methods
- 21 experiments were performed in 18 healthy adults aged 25–48 years with no neurological disease; tungsten microelectrodes recorded from muscle nerve fascicles of the median, peroneal, and tibial nerves.
- 30 mechanoreceptive units were analysed, of which 28 fulfilled spindle-afferent criteria (21 probable group Ia, 7 probable group II; 2 were group Ib tendon organs). Altogether, 127 Jendrassik manoeuvres were performed on the 28 spindle afferents.
- Units were tested at constant muscle length, during passive stretch, during tendon taps, and during electrically induced twitches; joint angle, torque, and EMG of receptor-bearing muscles were monitored. The reinforcement manoeuvre was fist clenching or forced separation of interlocked clenched hands.
Limitations
- Stated: EMG electrodes may not have been positioned to record all contracting muscle portions, so some torque changes without detectable EMG could still reflect undetected active contraction.
- Stated: single-fibre sampling may be biased, which prompted multiunit recordings; distinguishing group Ia from group II fibres was sometimes difficult.
- Evident from the text: the sample was small and limited to healthy adults, and sympathetic bursts or body displacement could obscure or confound recordings; the paper notes that sympathetic activity sometimes obscured the afferent activity under study.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
0 of 18 cited sources checked · 0 supported · 0 flagged
- Findingown data
The unit almost ceases firing when torque falls at the end of the manoeuvre.
“The unit almost ceases firing whent torque falls at the end of the manoeuvre.”
Quote in the paperNot a substantial claim - Findingcitation
The Valsalva-type manoeuvre is particularly potent in enhancing the sympathetic pulse synchronous outflow to the muscles.
“this type of manoeuvre is particularly potent in enhancing the sympathetic pulse synchronous outflow to the muscles.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Delius et al., 1972 source
Not checked in the free run.
- Findingown data
In relaxed muscles, no evidence of increased dynamic spindle sensitivity has been found to accompany tendon jerk reinforcement.
“In re- laxed muscles no evidence of increased dynamic spindle sensitivity has been found to accompany tendon jerk reinforcement.”
Quote in the paperSubstantial claim - Findingown data
In manoeuvres where a spindle response was accompanied by EMG activity in the receptor-bearing muscle, the increase in fibre frequency was better correlated with the time course of the EMG events than with the duration of the manoeuvre.
“frequency was better correlated with the time in the Figure ).In C the extrafusal contraction course of the EMG events than with the dura-was weak, as seen in the torque and EMG tion of the manoeuvre (Fig. 3).”
Quote in the paperSubstantial claim - Findingown data
Fist clenching causes a marked enhancement of sympathetic efferent activity recorded in a peroneal muscle nerve fascicle of a subject with mild hypertension.
“Figure 8 illustrates how fist clenching causes a marked enhancement of the sympa- thetic efferent activity recorded in a peroneal muscle nerve fascicle of a subject with mild hypertension.”
Quote in the paperNot a substantial claim
- Findingown data
Any change in spindle activity was always accompanied by EMG or torque changes involving the extrafusal muscle.
“Any change in spindle activity was always accompanied by EMG or torque changes involving the extrafusal muscle.”
Quote in the paperSubstantial claim - Findingown data
In three fibres the reinforcement led to a decrease in frequency in some tests.
“In three fibres the reinforcement led to a decrease in frequency in some tests.”
Quote in the paperNot a substantial claim - Findingown data
No differences were found between firm clenching of one fist and the classical Jendrassik manoeuvre.
“No differences were found between these manoeuvres and, hereafter, both are referred to as the 'Jendrassik manoeuvre'.”
Quote in the paperSubstantial claim - Findingown data
Prominent changes in torque and frequency occur before the first manoeuvre as the subject prepared for it.
“Prominent chaniges in torque and frequency, indicated by the ar-row, occur before the first manoeuvre as the subject preparedfor it.”
Quote in the paperNot a substantial claim - Findingown data
The Jendrassik manoeuvre had no effect on afferent spindle discharges as long as there were no EMG signs of unintentional contractions in the receptor-bearing muscle and no mechanotransducer signs of unintentional positional changes altering the load on that muscle.
“The manoeuvres had no effect upon the afferent spindle discharges as long as there were no EMG signs of unintentional contractions occurring in the receptor-bearing muscle and no mechanotransducer signs of unintentional positional changes altering the load on that muscle.”
Quote in the paperSubstantial claim- Rests on an assumption: The EMG and torque recordings used were sensitive enough to detect any unintentional contraction or positional change in the receptor-bearing muscle that could alter spindle discharge.
- Findingown data
In some of the most forceful Jendrassik manoeuvres, subjects sometimes held their breath and made an expiratory effort against closed glottis as in the Valsalva manoeuvre.
“In some of the most forceful Jendrassik manoeuvres performed in the present study the subjects sometimes held their breath and made an expiratory effort against closed glottis as in the Valsalva manoeuvre.”
Quote in the paperNot a substantial claim - Findingown data
Using different means of testing the position and velocity sensitivity of spindles, effects attributable to selective activation of static or dynamic fusimotor fibres were sought, but without success.
“Using different means of testing the position-and velo- city sensitivity of spindles, effects attributable to selective activation of static or dynamic fusi- motor fibres have been sought, but without success.”
Quote in the paperSubstantial claim - Findingown data
In the same fibre, discharge frequency decreases in two manoeuvres, in parallel with torque.
“In B, discharge frequency decreases in two manoeuvres, in parallel with torque.”
Quote in the paperNot a substantial claim - Findingown data
The 28 spindle afferent fibres had a wide spectrum of receptor sensitivity to active or passive displacement.
“The 28 spindle afferent fibres had a wide spectrum of receptor sensitivity to active or passive displacement.”
Quote in the paperNot a substantial claim - Findingown data
In those manoeuvres where a spindle response occurred without detectable EMG activity, changes in discharge frequency could be correlated with changes in torque.
“In those manoeuvres where a spindle response occurred without detectable EMG activity the changes in discharge frequency could be cor- related with changes in torque.”
Quote in the paperSubstantial claim - Findingown data
In some intrafascicular recording sites, pulse synchronous sympathetic bursts obscured the afferent activity primarily under study.
“Indeed, in some intrafascicular recording sites the pulse syn- chronous sympathetic bursts have obscured the afferent activity primarily under study.”
Quote in the paperNot a substantial claim - Findingown data
Only four spindle afferent fibres increased their discharge frequency in every reinforcement manoeuvre with which they were tested.
“Only four spindle afferent fibres increased their discharge frequency in every reinforcement manoeuvre with which they were tested.”
Quote in the paperNot a substantial claim - Findingown data
During reinforcement, a subject unintentionally tensed forearm muscles, producing a greater discharge frequency of a group Ib afferent fibre from a Golgi tendon organ in flexor digitorum profundus.
“During the reinforcement, the subject unintentionally tensed the forearm muscles, thus producing a greater discharge frequency of the lb afferent fibre.”
Quote in the paperNot a substantial claim - Findingown data
The responses of most of the fibres that changed discharge frequency during reinforcement were not reproducible.
“However, the responses of most of these fibres were not reproducible (see Table 2).”
Quote in the paperSubstantial claim - Findingown data
The variability of response from one test to the next was especially pronounced for those afferent fibres which exhibited extreme sensitivity to displacement.
“The variability of response from one test to the next was especially pronounced for those afferent fibres which exhibited the extreme sensitivity to displacement referred to above.”
Quote in the paperNot a substantial claim - Findingown data
In one group Ia fibre, slow periodic irregularities in the frequency plot corresponded closely to respiratory oscillations visible in the torque recording at high gain.
“In Fig. lB the frequency plot of another group Ta fibre contains slow periodic irregularities that correspond closely to the respiratory oscillations which became visible in the torque recording only when displayed at high gain.”
Quote in the paperNot a substantial claim - Findingown data
Marked changes in sympathetic vasoconstrictor outflow to the muscles may accompany reinforcement manoeuvres.
“Marked changes in sympathetic vasocon- strictor outflow to the muscles may accompany reinforcement manoeuvres.”
Quote in the paperNot a substantial claim - Findingown data
Spindle afferent fibres were further classified as probably group Ia (21 fibres) or probably group II (seven fibres) depending on their regularity of discharge and sensitivity to the velocity of stretching movements.
“Depending on their regularity of discharge and their sensitivity to the velocity of stretching movements, spindle afferent fibres were further classified as probably group Ia (21 fibres) or probably group II (seven fibres), although a clear distinction was sometimes difficult.”
Quote in the paperNot a substantial claim - Findingcitation
Of the 30 mechanoreceptive units analysed, 28 fulfilled the criteria of muscle spindle afferent fibres as described by Vallbo (1970a).
“Of the 30 mechanoreceptive units analysed in the present study, 28 fulfilled the criteria of muscle spindle afferent fibres as described by Vallbo (1970a).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Vallbo (1970a)
Not checked in the free run.
- Interpretationown data
The results provide no evidence for fusimotor sensitization of spindles in muscles remaining relaxed during the Jendrassik manoeuvre.
“The results provide no evidence for fusimotor sensitization of spindles in muscles remaining relaxed during the Jendrassik manoeuvre”
Quote in the paperSubstantial claim- Rests on an assumption: The EMG and torque recordings used were sensitive enough to detect any unintentional contraction or positional change in the receptor-bearing muscle that could alter spindle discharge.
- Interpretationown data
Few untrained persons would be able to relax completely in all distant muscles when being encouraged to perform a forceful Jendrassik manoeuvre.
“The present study suggests that few untrained persons would be able to relax completely in all distant muscles when being encouraged to perform a forceful Jendras- sik manoeuvre.”
Quote in the paperSubstantial claim - Interpretationreasoning
Many clinical reinforcement tests are probably associated with unintentional contractions in the muscle to be tested.
“Therefore, many clinical re- inforcement tests are probably associated with unintentional contractions in the muscle to be tested.”
Quote in the paperSubstantial claim - Interpretationcitation
The reflex enhancement noted during such contractions is due, not to a greater afferent input, but to altered processing of the afferent volley within the cord.
“As suggested in Fig. 6, the reflex enhancement noted during such contractions is due, not to a greater afferent in- put, but to altered processing ofthe afferent volley within the cord (cf.Clare and Landau, 1964).”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Clare and Landau, 1964
Not checked in the free run.
- Premisecitation
To date, the segmental phasic stretch reflex represents the only documented exception to the principle of alpha-gamma coactivation.
“To date, the segmental phasic stretch reflex represents the only documented exception to the principle of alpha-gamma co- activation (Burg et al., 1973, 1974; Hagbarth et al., 1975b).”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites Burg et al., 1973, 1974
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- cites Hagbarth et al., 1975b source
Not checked in the free run.
- Interpretationreasoning
The occurrence of profound changes in sympathetic outflow unaccompanied by changes in muscle spindle activity, as seen in this and earlier studies, provides evidence that the physiological effects of the sympathetic nervous system on spindle function in man are negligible.
“However, the occurrence of profound changes in sympathetic outflow unaccompanied by changes in muscle spindle activity, as seen in this and earlier studies, provides evidence that the physiological effects of the sympathetic nervous system on spindle function in man are negligible.”
Quote in the paperSubstantial claim - Premisecitation
The principle of alpha-gamma coactivation was established for human motor acts by studies of isometric and isotonic voluntary contractions.
“This principle was established for human motor acts by studies of isometric and isotonic voluntary con- tractions (Hagbarth and Vallbo, 1968; Vallbo, 1970b, 1971, 1972, 1974).”
Quote in the paperSubstantial claim0 of 2 sources checked- cites Hagbarth and Vallbo, 1968 source
Not checked in the free run.
- cites Vallbo, 1970b, 1971, 1972, 1974
Not checked in the free run.
- Interpretationreasoning
In some manoeuvres, torque changes may have been due to active contraction of receptor-bearing muscles not detected because EMG electrodes were not appropriately positioned to record the potentials of the contracting muscle portions.
“With some of these manoeuvres the torque changes may have been due to active contraction of the receptor- bearing muscles not detected since the EMG electrodes were not appropriately positioned to record the potentials of the contracting muscle portions.”
Quote in the paperSubstantial claim - Premisecitation
The findings of Burg et al. (1974) implied an exception to the principle of alpha-gamma coactivation in motor control.
“The findings of Burg et al. (1974) implied an excep- tion to the principle of alpha-gamma co- activation in motor control.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Burg et al. (1974)
Not checked in the free run.
- Premisenone given
Recordings of spindle afferent activity in awake human subjects have provided increasing evidence that the supraspinal influences which control movement and posture are directed to the skeletomotor and fusimotor systems in parallel.
“Thus far, the recordings of spindle afferent activity in awake human subjects have pro- vided increasing evidence that the supraspinal influences which control movement and posture are directed to the skeletomotor and fusimotor systems in parallel.”
Quote in the paperSubstantial claim - Interpretationown data
In the present study, evidence has been presented that the unintentional postural adjustments and associated movements that may accompany the performance of a consciously directed motor act are also carried out according to the principle of alpha-gamma coactivation.
“In the present study, evidence has been presented that the unintentional postural adjust- ments and 'associated' movements that may accompany the performance of a consciously directed motor act are also carried out according to the principle of alpha-gamma coactivation.”
Quote in the paperSubstantial claim
- May combine two claims. 17
- Classified as probably not a substantial claim. 14
- The quote only partly states this claim. 1
May combine two claims.
Findingown dataIn a tibialis anterior group Ia fibre at constant length, one Jendrassik manoeuvre of four is associated with a significant increase in discharge frequency, but this is correlated with an increase in torque.
“In A, one Jelndrassik manioeuvre offour is associated with a significanit inicrease in discharge frequency but this is correlated with ani increase in torque.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataOnly 5000 of the spindles tested altered discharge frequency during reinforcement manoeuvres, and in most of these the effects were variable, a decrease in frequency being occasionally recorded.
“In the present study, however, only 5000 of the spindles tested altered discharge frequency dur- ing reinforcement manoeuvres, and in most of these the effects were variable, a decrease in frequency being occasionally recorded.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataIn Fig. 5, reinforcement had no effect on integrated neural activity during passive stretching at fast rates (A) and relatively slow rates (B).
“In Fig. 5 the lack of effect of reinforcement on integrated neural activity is shown during passive stretching at fast rates (A) and relatively slow rates (B).”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing), S4 (based).
Findingnone givenTwo afferent fibres were regarded as group Ib afferent fibres from Golgi tendon organs.
“Two afferent fibres were regarded as group Ib afferent fibres from Golgi tendon organs”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
Findingown dataWeak voluntary contractions may be accompanied not only by increased static spindle firing but also by increased dynamic spindle responses to tendon percussion.
“We have observed that weak voluntary contractions may be accompanied not only by increased static spindle firing but also by in- creased dynamic spindle responses to tendon percussion (unpublished observations).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataIn Fig. 6, percussion of the Achilles tendon elicited an afferent neural discharge and a reflex contraction of the triceps surae.
“In Fig. 6 percussion of the Achilles tendon elicited an afferent neural discharge and a reflex contraction of the triceps surae.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataThe reinforcement manoeuvre in Fig. 6B produced increases in reflex torque and reflex EMG but no increase in size of the afferent neural volley.
“The reinforce- ment manoeuvre performed in B produced in- creases in reflex torque and reflex EMG but no increase in size of the afferent neural volley.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataWith careful monitoring of the state of the extrafusal muscle, the present study has been unable to confirm previous assertions that there is a marked increase of muscle spindle activity in a relaxed muscle during contraction of a remote muscle and that fusimotor sensitization contributes to reflex reinforcement.
“With careful monitoring of the state of the extrafusal muscle, the present study has been unable to confirm these assertions.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataIn a tibialis anterior group II fibre, discharge increased slightly during a Jendrassik manoeuvre, but this was correlated with a slight increase in torque and the appearance of EMG potentials from a single motor unit in tibialis anterior muscle.
“In C, the dis- charge of a tibialis anterior group II fibre increased slightly clurinig a Jenidrassik manoeuvre (indicated by the solid bar) but this was correlated with a slight increase in torque (second trace) and the appearance of EMG potentials from a single motor unit in tibialis aniterior muscle (third trace).”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataOf the 28 spindle afferent fibres, 18 were classified as 'definite spindle afferents' on the basis of their discharge during the relaxation phase of electrically-induced twitches or mechanically-induced tendon jerks, and the other 10 were denoted 'probable spindle afferents'.
“Of these 28 fibres, 18 were also tested using electrically-induced muscle twitches or mechanically-induced tendon jerks, and on the basis of their discharge during the relaxation phase of the twitch they were classified as 'definite spindle afferents', whereas the other 10 units were denoted as 'probable spindle afferents'.”
Quote in the paperNot a substantial claimMay combine two claims.
Findingown dataThe reinforcement manoeuvre failed to affect the response of a single Ia afferent fibre to tendon percussion, although a greater discharge was seen during the relaxation phase of the enhanced reflex contractions.
“The reinforcement manoeuvre also failed to affect the response of this fibre to tendon percussion, although, as may be expected, a greater discharge was seen during the relaxation phase of the enhanced reflex contractions.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataIn a peroneus group Ia fibre, spindle activation coincides with the onset of the Jendrassik manoeuvre but outlasts each manoeuvre and correlates more closely with the unintentional contraction/traction that developed in the peroneal muscles.
“In A, spindle activationi coitncides wit/h the onset of the manoeuvre but outlasts each manoeuvre anid correlates more closely with the unintentional cont-1 o/S tractioni that developed in the peroneal muscles.”
Quote in the paperSubstantial claimMay combine two claims.
Findingown dataAt seemingly constant muscle length, some spindle fibres maintained a relatively stable mean discharge frequency, but others were extremely sensitive to minor disturbances.
“At seemingly constant muscle length, some fibres maintained a relatively stable, mean discharge frequency, but others proved extremely sensitive to minor disturbances”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationBurg et al. (1973, 1974) reported that during the Jendrassik manoeuvre spindle afferent activity accelerated in remote relaxed muscles and that there was an irregular spontaneous spindle discharge which varied in frequency with the subject's degree of attention.
“Diverging results were recently reported by Burg et al. (1973, 1974) who during the Jendras- sik manoeuvre found an acceleration of spindle afferent activity in remote relaxed muscles and an irregular spontaneous spindle discharge which varied in frequency with the subject's degree of attention.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Burg et al. (1973, 1974)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Probably not a substantial claim: may not pass S3 (load-bearing).
PremisecitationHagbarth and Vallbo (1968) noted a marked enhancement of activity in muscle spindle afferent fibres during voluntary isometric contraction of the leg or arm muscles in which the receptors were located.
“In the initial study dealing with recordings from muscle spindle afferent nerve fibres in man, Hagbarth and Vallbo (1968) noted a marked enhancement of the activity in these fibres during voluntary isometric contraction of the leg or arm muscles in which the receptors were located.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Hagbarth and Vallbo (1968) source
Not checked in the free run.
Classified as probably not a substantial claim.
Study design and conductreasoningThe high sensitivity of some spindle afferents made it crucial that equally sensitive measures be used to monitor possible disturbing forces.
“a sensitivity which made it crucial that equally sensitive meas- ures be used to monitor possible disturbing forces.”
Quote in the paperSubstantial claimProbably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).
InterpretationcitationThese findings seem to imply that in awake human subjects intrafusal fibres are exposed to a sustained fusimotor outflow varying in strength during various manoeuvres without concurrent changes in the skeletomotor outflow to the receptor-bearing muscles.
“These findings seem to imply that in awake human subjects intrafusal fibres are exposed to a sustained fusimotor outflow varying in strength during various manoeuvres without concurrent changes in the skeletomotor outflow to the receptor-bearing muscles.”
Quote in the paperNot a substantial claimProbably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationAnimal experiments have shown that differential effects on the skeletomotor and fusimotor systems can occur in conditioned movements and can be induced by stimulation of different regions of the cortex, basal ganglia, and brain stem.
“Although animal experiments have shown that differential effects on the skeletomotor and fusi- motor systems can occur in conditioned movements (Buchwald and Eldred, 1962) and can be induced by stimulation of different regions of the cortex, basal ganglia, and brain stem, the signifi- cance of these findings to the normal control of movements, particularly in man, is conjectural.”
Quote in the paperNot a substantial claim0 of 1 sources checked- cites Buchwald and Eldred, 1962
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.
PremisecitationMore recently, the principle of alpha-gamma coactivation has been shown to apply to rapid alternating movements and the involuntary tremulous movements of patients with Parkinson's disease.
“More recently, the principle has been shown to apply to rapid alternating movements (Hagbarth et al., 1975a) and the involuntary tremulous movements of patients with Parkinson's disease (Hagbarth et al., 1975b).”
Quote in the paperNot a substantial claim0 of 2 sources checked- cites Hagbarth et al., 1975a
Not checked in the free run.
- cites Hagbarth et al., 1975b
Not checked in the free run.
Classified as probably not a substantial claim. The quote only partly states this claim.
Study design and conductown dataCompliance with the instruction to remain relaxed in all muscles other than those taking part in the manoeuvre was checked for the receptor-bearing muscles by EMG and torque recordings.
“Compliance with this request was checked for the receptor-bearing muscles by the recordings of EMG and torque described earlier.”
Quote in the paperSubstantial claim- Rests on an assumption: The EMG and torque recordings used were sensitive enough to detect any unintentional contraction or positional change in the receptor-bearing muscle that could alter spindle discharge.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductnone givenThe strain gauge bridge was adjusted so that small changes in torque down to 0.05 Nm could be readily discerned.
“the sensitivity of the bridge being adjusted in such a way that small changes in torque down to 0.05 Nm could be readily discerned.”
Quote in the paperNot a substantial claimMay combine two claims.
Interpretationown dataA change in firing frequency in response to the Jendrassik manoeuvre is not a specific characteristic of muscle spindles, and this criterion cannot be used as a means of identification of spindles.
“Thus it is clear that a change in firing frequency in response to the Jendrassik manoe- uvre is not a specific characteristic of muscle spindles, and this criterion cannot be used as a means of identification of spindles.”
Quote in the paperSubstantial claimClassified as probably not a substantial claim.
PremisecitationNo reduction in afferent stretch responses was seen after lidocaine blocks of the muscle nerve proximal to the recording site.
“and no reduction in afferent stretch responses was seen after lidocaine blocks of the muscle nerve proximal to the recording site (Hagbarth et al., 1970b, 1975a; Wallin et al., 1973).”
Quote in the paperSubstantial claim0 of 2 sources checked- cites Hagbarth et al., 1970b, 1975a
Not checked in the free run.
- cites Wallin et al., 1973
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing).
InterpretationreasoningAn increased afferent percussion discharge during contraction may simply be a reflection of a more effective transmission of the tendon percussion wave to the spindle receptors.
“Any contraction alters the mechanical state of the muscle and it is conceivable that an increased afferent percussion discharge is simply a reflection of a more effective transmission of the tendon percussion wave to the spindle receptors.”
Quote in the paperNot a substantial claimClassified as probably not a substantial claim.
Study design and conductcitationThe electrode was assessed as having impaled a pure muscle nerve fascicle by multiunit afferent discharges in response to passive muscle stretch and tendon taps with concurrent lack of afferent responses to skin strokings and other superficial cutaneous stimuli.
“a main criterion be- ing the multiunit afferent discharges appearing in re- sponse to passive muscle stretch and tendon taps with concurrent lack of afferent responses to skin strok- ings and other superficial cutaneous stimuli.”
Quote in the paperSubstantial claim0 of 1 sources checked- cites Hagbarth et al., 1975a
Not checked in the free run.
May combine two claims.
PremisecitationAs long as the receptor-bearing muscles remained relaxed, Swedish investigators found no evidence for varying fusimotor tonus: dynamic and static spindle responses to passive stretch were not appreciably influenced by the Jendrassik manoeuvre or by changes in the attentive state of the subject.
“As long as the receptor-bearing muscles re- mained relaxed, the Swedish investigators found in awake human subjects no evidence for varying fusimotor tonus-that is, the dynamic and static spindle responses to passive stretch were not appreciably influenced by the Jendrassik manoeuvre (Hagbarth and Vallbo, 1968) or by changes in the attentive state of the subject (Vallbo, 1972)”
Quote in the paperSubstantial claim0 of 2 sources checked- cites Hagbarth and Vallbo, 1968 source
Not checked in the free run.
- cites Vallbo, 1972
Not checked in the free run.
Probably not a substantial claim: may not pass S3 (load-bearing).
Study design and conductreasoningEMG activity was monitored on a loudspeaker and integrated, which aided identification of low amplitude distant potentials difficult to distinguish from background noise.
“These measures aided identification of low amplitude distant potentials which were difficult to distinguish from background noise in the direct recording.”
Quote in the paperNot a substantial claim
The paper relies on this without support.
The EMG and torque recordings used were sensitive enough to detect any unintentional contraction or positional change in the receptor-bearing muscle that could alter spindle discharge.
“Compliance with this request was checked for the receptor-bearing muscles by the recordings of EMG and torque described earlier.”
“a sensitivity which made it crucial that equally sensitive meas- ures be used to monitor possible disturbing forces.”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The same reinforcing effect was also seen in the H-reflex, which is independent of the spindle receptors and hence is presumably not affected by the gamma innervation.
“However, the same reinforcing effect was also seen in the H-reflex (Hagbarth et al., 1975, Dowman and Wolpaw, 1988), which is independent of the spindle receptors and hence is presumably not affected by the gamma innervation.”
From Standardization of the Jendrassik maneuver in Achilles tendon tap reflex (2018) · cites this paper as Hagbarth et al., 1975
The main mechanism behind the JM is not fusimotor activation.
“Different studies, using microneurography and muscle spindle conditioning, discussed that the main mechanism behind the JM is not the fusimotor activation (Gregory et al., 2001, Hagbarth et al., 1975).”
From Standardization of the Jendrassik maneuver in Achilles tendon tap reflex (2018) · cites this paper as Hagbarth et al., 1975
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Definite-spindle count differs between the text and Table 2
MinorThe text reports 18 definite spindle afferents, but the four definite-spindle rows in Table 2 list 9, 4, 4, and 2 units, totaling 19.
“Of these 28 fibres, 18 were also tested using electrically-induced muscle twitches or mechanically-induced tendon jerks, and on the basis of their discharge during the relaxation phase of the twitch they were classified as 'definite spindle afferents', whereas the other 10 units were denoted as 'probable spindle afferents'.”
“1. Deftilite spindle + (2) 1 I. Peroneal 9 2 7 0,+ (4) 4 0±os,-(I1) 1 Tibial 4 2 2 + (1) l 11 Peroneal 4 2 2 (, + (2) 1 1 Tibial 2 2 0”
Cites
General Characteristics of Sympathetic Activity in Human Muscle Nerves
Delius, W., Hagbarth, K. ‐., Hongell, A., & Wallin, B. G. (1972) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1972.tb05157.x · Cited by 831 · see citing works
Self-citationVallbo, Å. B. (1974) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1974.tb05594.x · Cited by 370 · see citing works
Manoeuvres affecting sympathetic outflow in human muscle nerves
Delius, W., Hagbarth, K. ‐., Hongell, A., & Wallin, B. G. (1972) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1972.tb05158.x · Cited by 316 · see citing works
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Neurophysiology Studied in Man
Gilman, S. (1973) · Neurology · doi:10.1212/wnl.23.10.1140 · Cited by 298 · see citing works
Discharge characteristics of human muscle afferents during muscle stretch and contraction
Hagbarth, K.-E., & Vallbo, Å. B. (1968) · Experimental Neurology · doi:10.1016/0014-4886(68)90156-8 · Cited by 204 · see citing works
Self-citationDischarge Patterns in Human Muscle Spindle Afferents during Isometric Voluntary Contractions
Vallbo, Å. B. (1970) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1970.tb04823.x · Cited by 176 · see citing works
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Afferent impulses in median nerve fascicles evoked by tactile stimuli of the human hand
Hagbarth, K. E., Hongell, A., Hallin, R. G., & Torebjörk, H. E. (1970) · Brain Research · doi:10.1016/0006-8993(70)90183-6 · Cited by 106 · see citing works
Self-citationThe effect of sympathetic stimulation on mammalian muscle spindles
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Slowly Adapting Muscle Receptors in Man
Vallbo, Å. B. (1970) · Acta Physiologica Scandinavica · doi:10.1111/j.1748-1716.1970.tb04667.x · Cited by 101 · see citing works
Muscle spindle activity in alternating tremor of Parkinsonism and in clonus
Hagbarth, K. E., Wallin, G., Lofstedt, L., & Aquilonius, S. M. (1975) · Journal of Neurology, Neurosurgery & Psychiatry · doi:10.1136/jnnp.38.7.636 · Cited by 100 · see citing works
Self-citationMuscle spindle activity in man during voluntary fast alternating movements.
Hagbarth, K. E., Wallen, G., & Löfstedt, L. (1975) · Journal of Neurology Neurosurgery & Psychiatry · doi:10.1136/jnnp.38.7.625 · Cited by 86 · see citing works
Self-citationActivity of muscle spindles during muscle twitch and clonus in normal and spastic human subjects
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Assessment of fusimotor contribution to reflex reinforcement in humans
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The effect of gamma fibre block on afferent muscle nerve activity during voluntary contractions.
Hagbarth, K. E., Hongell, A., & Wallin, B. G. (1970) · PubMed · Cited by 20 · see citing works
Self-citationThe effect of adrenaline on the response to muscle vibration in man.
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Recordings from Muscle Afferents in Parkinsonian Rigidity1
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Self-citationA transistor instantaneous frequency meter
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Flagged first, then by citations
Research works printed but not linked: 1
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Cited by
Sorted by citations
Interaction of the Jendrássik maneuver with segmental presynaptic inhibition
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Implications of neural networks for how we think about brain function
Robinson, D. A. (1992) · Behavioral and Brain Sciences · doi:10.1017/s0140525x00072563 · Cited by 107 · see citing works
Mechanism of monosynaptic reflex reinforcement during Jendrassik manoeuvre in man.
Bussel, B., Morin, C., & Pierrot-Deseilligny, E. (1978) · Journal of Neurology, Neurosurgery & Psychiatry · doi:10.1136/jnnp.41.1.40 · Cited by 84 · see citing works
Normal values of patellar and ankle tendon reflex latencies
Frijns, C. J. M., Laman, D. M., van Duijn, M. A. J., & van Duijn, H. (1997) · Clinical Neurology and Neurosurgery · doi:10.1016/s0303-8467(96)00593-8 · Cited by 78 · see citing works
An investigation into mechanisms of reflex reinforcement by the Jendrassik manoeuvre
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Standardization of the Jendrassik maneuver in Achilles tendon tap reflex
Ertuglu, L. A., Karacan, I., Yilmaz, G., & Türker, K. S. (2018) · Clinical Neurophysiology Practice · doi:10.1016/j.cnp.2017.10.003 · Cited by 20 · see citing works
- Authors
- Hagbarth, K. E., Wallin, G., Burke, D., & Lofstedt, L.
- Affiliations
- Uppsala University Hospital (SE)
- ORCID
- Burke, D
- Venue
- Journal of Neurology, Neurosurgery & Psychiatry
- Publisher
- BMJ
- Published
- 1975-12-01
- Volume
- 38
- Issue
- 12
- Pages
- 1143-1153
- ISSN
- 0022-3050 (ISSN-L)
- PMC
- PMC492180
- OpenAlex
- W2106244872
- Cited by
- 107
- References
- 21
- Citations by year
- 2023: 1 · 2022: 2 · 2021: 1 · 2020: 1 · 2019: 3 · 2018: 1 · 2017: 1 · 2015: 1 · 2014: 1 · 2012: 2
- FWCI
- 10.33
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Neurology Neurosurgery & Psychiatry (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Physical Sciences › Engineering › Biomedical Engineering › Muscle activation and electromyography studies
- Life Sciences › Neuroscience › Cognitive Neuroscience › Motor Control and Adaptation
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
- Keywords
- muscle spindles, fusimotor system, spindle afferents, voluntary muscle contraction, deep tendon reflexes, coactivation, mechanoreceptors, tibial nerve, peroneal nerve, median nerve
- MeSH terms
- Adult, Electromyography, Humans, Mechanoreceptors, Muscles, Muscle Spindles, Reflex, Stretch, Sympathetic Nervous System, Tendons
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-11.
Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-11.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
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